1. Field of the Invention
The invention relates to an electromagnetic rotary electric machine in which a stator and a rotor are disposed facing each other.
2. Description of Related Art
As described in Japanese Patent Application Publication No. 2009-112091 (JP 2009-112091 A), an electromagnetic rotary electric machine is available, in which a stator and a rotor are disposed facing each other, and that includes salient poles provided at a plurality of locations on the rotor that are spaced from each other in the circumferential direction of the rotor, rotor windings that are wound around the salient poles and that are separate from each other, and diodes that are connected to respective rotor windings. The diodes each rectify the electric current that flows through a corresponding one of the rotor windings so that salient poles adjacent to each other in the circumferential direction of the rotor are magnetized in opposite directions. The stator has teeth that are provided at a plurality of locations on a stator core that are spaced from each other in the circumferential direction. Around the teeth of the stator, stator windings of a plurality of phases are wound by a concentrated winding method. By passing alternating electric currents of a plurality of phases through the stator windings of the plurality of phases, a rotating magnetic field that rotates in a circumferential direction is generated. Due to spatial harmonics that are harmonic components that occur in a distribution of magnetomotive forces produced around the stator, induced currents are created in the rotor windings, so that N poles and S poles are formed in the salient poles alternately in the circumferential direction of the rotor and thus torque is produced on the rotor. At this time, as the currents rectified by the diodes flow through the rotor windings, the salient poles are magnetized to produce magnets whose magnetic poles are fixed.
In such an electromagnetic rotary electric machine, the salient poles interact with the rotating magnetic field of the stator so that torque acts on the rotor. Besides, the torque that acts on the rotor can be efficiently increased by utilizing a harmonic component of the magnetic field formed by the stator.
In this rotary electric machine, the salient poles of the rotor are provided with rotor windings. When the rotor rotates, centrifugal force acts on the rotor windings, exerting force that urges the rotor windings to the radially outer side. As a countermeasure to this, it is conceivable to provide winding wire retention means for retaining the rotor windings on the salient poles. With regard to this, there is room for improvement in terms of increasing the strength in retaining the rotor windings against centrifugal force that is achieved by the winding wire retention means.